Regenerative Thrust Chamber Cooling to Cut Fuel Overuse

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Solution Overview

Problem

Existing thrust chamber devices inefficiently utilize fuel components due to transpiration cooling, leading to incomplete combustion and the need for excess fuel injection, which increases weight and pressure loss.

Innovation Solution

Implement a regenerative cooling system for the inner and outer nozzle walls using a coolant to absorb heat, driving a turbine for conveying devices, allowing for efficient fuel delivery and reducing the combustion chamber length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If transpiration cooling is used to cool the outer nozzle wall with the first fuel component, then the outer nozzle wall is cooled effectively, but more fuel must be injected than required for optimal combustion, leading to incomplete combustion and increased weight

Engineering Contradiction:
Improveouter nozzle wall temperatureVSAvoidfuel injection quantity
Core Design Contradiction:
TemperatureVSQuantity of substance

Solution Approach 1:

The cooling system is segmented into separate inner and outer coolant channels, allowing independent cooling of the inner nozzle wall and outer nozzle wall. This segmentation enables precise thermal management without requiring excess fuel injection, as each wall can be cooled independently with optimized coolant flow rates.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A coolant is introduced as an intermediary substance to transfer heat from the nozzle walls to the combustion chamber. The coolant absorbs heat from the inner and outer nozzle walls through dedicated cooling channels, preventing direct heat transfer to the propellant and eliminating the need for excess fuel injection that would otherwise be required for cooling.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a conventional cylindrical combustion chamber design is used, then the structure is simple, but the combustion chamber length is excessive, causing pressure loss due to enthalpy absorption by the coolant

Engineering Contradiction:
Improvecombustion chamber structureVSAvoidcombustion chamber length
Core Design Contradiction:
Device complexityVSLength of moving object

Solution Approach 1:

The combustion chamber adopts a curved, annular cross-sectional design with the coolant channels following the curved path between the inner and outer nozzle walls. This curved geometry reduces the axial length of the combustion chamber compared to a conventional cylindrical design, minimizing pressure loss while maintaining effective cooling surface area.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The cooling system utilizes the radial dimension by introducing coolant channels between the inner and outer nozzle walls, creating a three-dimensional cooling path. This allows heat to be extracted from both the inner and outer surfaces simultaneously, reducing the required axial length of the combustion chamber compared to conventional one-dimensional cooling designs.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Temperature

If the first fuel component is used for cooling the outer nozzle wall, then the outer nozzle wall is cooled, but the fuel is not completely combusted, resulting in energy loss

Engineering Contradiction:
Improveouter nozzle wall coolingVSAvoidcombustion efficiency
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The coolant serves multiple functions: it cools the inner nozzle wall, cools the outer nozzle wall, and drives the turbine for the conveying devices. By recovering the enthalpy of the heated coolant to drive the turbine, the system converts what would otherwise be wasted thermal energy into useful mechanical work, eliminating energy loss while maintaining effective cooling.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The heated coolant after absorbing heat from the nozzle walls is directed to drive a turbine that powers the conveying devices for injecting propellant components. This feedback loop recovers the thermal energy from the coolant and converts it into mechanical energy, ensuring complete utilization of the fuel's energy content and eliminating incomplete combustion losses.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The regenerative cooling system optimizes heat utilization, reduces chamber length by up to 50%, minimizes excess fuel injection, and prevents pressure loss, enabling lighter and more efficient thrust chamber operation.

Implementation Method 1

a regenerative cooling device for cooling the inner nozzle wall and the outer nozzle wall with a coolant

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

the heat or enthalpy absorbed by the coolant during the cooling of the two nozzle walls

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

in order to fully utilize the heat or enthalpy absorbed by the coolant during the cooling of the two nozzle walls for driving a drive device

Methodology Applied
Scientific EffectThermal energy conversion: Heat Engine

Data Source

PatentEP4211343B1Thrust chamber device and method for operating a thrust chamber device
Publication Date: 2026.02.25 DEUTSCHES ZENTRUM FÜR LUFT UND RAUMFAHRT E V
  • EP4211343B1 patent drawingFigure 1
  • EP4211343B1 patent drawingFigure 2
  • EP4211343B1 patent drawingFigure 3

AI summary

In order to improve a thrust chamber device, comprising a thrust chamber with a thrust space which has a first section, a second section which adjoins the latter, and a third section which adjoins the second section, wherein the thrust space is delimited in all three sections by an outer nozzle wall with an outer thrust space surface which tapers in the first and second section towards the third section, widens away from the second section in the third section, and a narrowest point is formed at the transition from the second section to the third section, wherein the first section is delimited by an inner nozzle wall with an inner thrust space surface which tapers towards the second section, wherein an annular combustion chamber which extends over the first section is formed between the inner thrust space surface and the outer thrust space surface, in such a way that a thrust chamber device can be operated more efficiently, it is proposed that the thrust chamber device comprises a regenerative cooling means for cooling the inner nozzle wall and the outer nozzle wall by way of a coolant. Furthermore, an improved method for operating a thrust chamber device is proposed.